C # Generic Dictionary

1. namespace:
　　 System. Collections. Generic (Assembly: mscorlib)
2. Description:
1) ing from a group of keys to a group of values. Each add item is composed of a Value and its associated keys.
2) any key must be unique.
3) The key cannot be null reference null (in VBNothing). If the value is of the reference type, it can be null.
4), the Key and Value can be of any type (string, int, custom class, etc)
3. Creation and initialization:
　　 Dictionary <int, string> myDictionary = new Dictionary <int, string> ();
4. Add elements:
MyDictionary. Add ("C #", 0 );
MyDictionary. Add ("C ++", 1 );
MyDictionary. Add ("C", 2 );
MyDictionary. Add ("VB", 2 );
5. Search for the element By Key:
If (myDictionary. ContainsKey ("C #"))
{
Console. WriteLine ("Key: {0}, Value: {1}", "C #", myDictionary ["C #"]);
}
6. traverse the element By KeyValuePair
Foreach (KeyValuePair <string, int> kvp in myDictionary)
{
Console. WriteLine ("Key = {0}, Value = {1}", kvp. Key, kvp. Value );
}
7. Only traverse the key By Keys attribute:
Dictionary <string, int>. KeyCollection keyCol = myDictionary. Keys;
Foreach (string key in keyCol/* string key in myDictionary. Keys */)
{
Console. WriteLine ("Key = {0}", key );
}
8. Only traverse the value By Valus attribute:
Dictionary <string, int>. ValueCollection valueCol = myDictionary. Values;
Foreach (int value in valueCol)
{
Console. WriteLine ("Value = {0}", value );
}
9. Remove the specified key value By Remove method:
MyDictionary. Remove ("C #");
If (myDictionary. ContainsKey ("C #"))
{
Console. WriteLine ("Key: {0}, Value: {1}", "C #", myDictionary ["C #"]);
}
Else
{
Console. WriteLine ("Key: C #" does not exist #");